Deep brain stimulation (DBS) of the subthalamic nucleus (STN) is effective treatment of Parkinson disease. Because the STN is small (9 X 7 X 4 mm) and it is not well visible using conventional imaging techniques, microelectrode recordings (MER) is used to ensure accurate detection of the STN borders. Commonly used MER techniques are subjective, time consuming and require an experienced electrophysiologist. Therefore, there is an urgent need to develop new methodologies for accurate and objective detection of the subthalamic nucleus during microelectrographic recordings. In this proposal we will utilize the multi-unit spiking activity (MSA) for detection of the STN borders. The MSA is characteristically elevated within the STN that facilitates unambiguous delineation of both the dorsal and ventral STN borders. The proposed approach enables exact and uniform placement of the stimulation electrodes that can improve outcome of the DBS surgeries. The proposed method is straightforward and has the potential to be used widely in clinical practice. The proposed project will involve work to translate the standalone, off-line MSA analysis into a real time analytical tool that is integrated into a currently available clinical electrophysiological workstation (FHC's Guideline 4000) for use in current functional neurosurgical procedures. PUBLIC HEALTH RELEVANCE: Project Narrative Deep brain stimulation of the subthalamic nucleus using electric current is an effective treatment of Parkinson disease (1-2). The accurate and reliable methods for detection of the target of stimulation are lacking. In this project, we implement a method for target detection based on an activity of the cells in the target (22) that enables accurate placement of the stimulating electrode. This approach can be widely used in clinical practice and it can improve outcomes of deep brain stimulation surgeries.